I found them very easy. I never used any spells for it.
Just use the holy weapon. It will freeze her almost constantly.
I thought the end game was a little too easy. I never used one single spell for the whole part after becoming the divine one. Except for going over that black river.
When using the holy weapon,I didn't even need to use heal potions or any other potions. Just hit her and she falls dead, without even hitting you (since she's frozen most of the time)
